This is a common problem in the RC aircraft community, LiPo batteries are generally recommended to be stored at about 70% of their capacity if they're going to sit unused for an extended period of time. In my experience it's probably ok to store them at full charge for around a week, after that, should store them at the reduced storage voltage.

Manufacturers state that when storing lithium polymer batteries for any length of time, we should store them ideally at a temperature of between 5ºC & 27ºC. The lower the temperature the better. The optimum voltage for long-term storage, as already mentioned is 3.8-3.85V per cell. Best practice after a days flying, is to charge them back to storage voltage using the storage function on your charger.

You could check Battery University website. It's basically a comprehensive encyclopaedia about battery technology, as the creator is a battery engineer itself working for a company called Cadex.

From what I know, there should not be a
problem as long as store lithium-based batteries above a certain threshold of State of Charge, in this case, 40%. And also according to the article, the lower the temperature you store them at, the higher the % of charge they will recover after a long time of storage.

This is the link, it's a pretty good reading with lots of technical info: